The converter I use has a rating of 45 amps, meaning it can, if asked, put out 45 amps of 12v DC. It will take a mostly discharged battery and put out a lot of charging current plus run all the 12v devices without complaining. Seems like you need to determine if your converter only puts out a tricklel charge, in which case it will not run much of anything.

Converter design has taken a decided turn for the better. The IntelliPower 9200 series I now use has a 4-stage smart charger built into it, and it will not boil out the batteries. My advice to those who have older, especially transformer-based heavyweights, is to swallow hard, upgrade and stop fussing with the older designs. The older ones are a losing proposition.

The converter in my Boler has a automatic switchover relay so that when shore power is provided, the battery is disconnected from the 12V circuits, and those circuits are powered solely by the converter. As a result, the battery does not get used at all when there is shore power. My converter does not have a charger, so in my case if the switchover fails, I could end up running on battery power only despite shore power being available. If the fan is the only thing using 12V power, that might resemble Dan's scenario.

I think it's worth knowing what is (or should be) connected to what in your specific trailer when shore power is on.

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__________________1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WDInformation is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.STATUS: No longer active in forum.

Per, the model I have is in a 2006 16 ft side dinette scamp. it was produced by American Enterprises Ind and is a model CS2000XL. the data sheet lists output as 12 voltes, 20 amps. I am looking into doing the smart charger thing, having already replaced my 1 year old deep cycle battery that came with the trailer. does this model give you any information?

One problem with the older converters (or newer ones without the Wizard or smart or intelligent card, better known descriptively as multi-stage chargers) is that they are NOT trickle chargers. TCs are normally capable of one amp or less, whereas the converters can put out four, eight or even more amps.

And that charge is usually at a fixed voltage. That's likely not a problem with a new battery which can accept a charge to a higher voltage, but I would guess that an older battery may not be able to accept the charge, so long-term charging (in storage, not on a weekend or even weeks where the 12VDC system is being used) is likely to hasten the demise of the battery.

BTW, exactly the same reasoning applies to the tempting 12VDC output of a generator or an uncontrolled solar panel -- The charger is just charging without regard to what the battery needs or can handle.

The above is not to say that the older, non-smart, trickle chargers are any less dangerous, they just take longer to damage a battery.

However, when you are camping and using the converter for its primary reason for existence, as a 12VDC power supply running off 120VAC shore power, the converter should be able to keep up with normal RV appliances for the RV size (Bulgemobiles have more 12VDC stuf, so they use bigger converters to run them).

Dan:
It doesn't tell me much, but maybe enough: 20 Amps should be adequate for both the battery and the appliances. I'd start out by making a list of all your 12v appliance amperages and adding it up according to how you might use these things. I think you'd find that there should be plenty of amps left for charging.

It may be that your converter is toast. I wouldn't fix it but replace it, things have moved on. The four-stage smart charger in mine will switch among the levels automatically, and you can get a cheap remote dongle with it whose blinks tell you exactly what is going on. In the 9200 series the Charge Wizard is built in, nothing more to add as in the 9100 series.

Leaving an old converter plugged in all the time (as we do here at home) may be convenient, but it may also boil out the battery. I know mine did.

I have emailed the manufacturer asking exactly how this thing functions. perhaps their answer will shed a bit more light on things. think i will get my hands on a voltmeter and check the battery level. maybe is just my imangination but i think we did not use the 12 volt system very much during those 6 days so if there was any charging being done at all it should have kept up. most days we were not there at all between 9 am and 5 pm so there was no 12 volt usage going on.

the manufacturer of the converter tells me the converter has a full charger built in, which reduces to a trickle when the battery is 98% charged. it will not boil the battery dry. it will also not restore a battery which is pulled down to nothing.

Apparently the converter charger needs to see some minimum voltage from the battery to function (I have heard that some converters won't work at all without a battery in place). You might try to 'trick' it by hooking up jumper cables to your vehicle battery to get the process started.

However, the sooner one recharges a depleted battery, the better it is for the battery, so I suggest you use a battery charger to restore it.

A fully depleted battery may allow too much current flow even at the charger's lowest output voltage, so it looks to the charger like the battery has one or more shorted cells; the charger reports an error and shuts off. A similar thing can happen at the opposite extreme: a very small battery doesn't take enough current and it looks like an open-cell error, and again the charger shuts off.

Dumber chargers don't know to shut off, so a manual or simple automatic charger (or the tow vehicle connectin) can get a flat battery charged enough so that the smart charger can finish it off properly; I have also got a flat battery to charge with my Vector by just resetting a few times - each attempt gets a bit of charge in and the voltage comes up to an acceptable level to continue normally (this won't work every time).

I don't think this conservative behaviour of smart chargers is a problem, because as Pete said under normal conditions the battery should never be discharged low enough to have a problem.

As a converter, it might be nice to be able run without a battery (mine does this normally), but if smoothly controlled voltage is important in the trailer, you want that battery in place to help.

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__________________1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WDInformation is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.STATUS: No longer active in forum.